Processes for the recovery of uranium from wet-process phosphoric acid using dual or single cycle continuous ion exchange approaches

ABSTRACT

In alternative embodiments, the invention provides processes and methods for the recovery, removal or extracting of, and subsequent purification of uranium from a wet-process phosphoric acid using a continuous ion exchange processing approach, where the uranium is recovered from a phosphoric acid, or a phos-acid feedstock using either a dual or a single stage extraction methodology. In both cases an intermediate ammonium uranyl-tricarbonate solution is formed. In alternative embodiments, in the dual cycle approach, this solution is contacted in a second continuous ion exchange system with a strong anion exchange resin then subsequently recovered as an acidic uranyl solution that is further treated to produce an intermediate uranyl peroxide compound which is ultimately calcined to produce the final uranium oxide product. In alternative embodiments, in the single cycle case, the intermediate ammonium uranyl-tricarbonate solution is evaporated to decompose the ammonium carbonate and produce an intermediate uranium carbonate/oxide solid material. These solids are digested in an acid medium, and then processed in the same manner as the secondary regeneration solution from the dual cycle process to produce an intermediate uranyl peroxide that is calcined to produce a final uranium oxide product.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/416,271, filed Jan. 21, 2015, which is a national phase applicationclaiming benefit of priority under 35 U.S.C. § 371 to Patent ConventionTreaty (PCT) International Application Ser. No: PCT/US2013/051417, filedJul. 21, 2013, which claims benefit of priority to U.S. ProvisionalPatent Application Ser. No. (“U.S. Ser. No.”) 61/674,297, filed Jul. 21,2012; and U.S. Ser. No. 61/716,630, filed Oct. 22, 2012. Theaforementioned applications are expressly incorporated herein byreference in their entirety and for all purposes.

TECHNICAL FIELD

This invention generally relates to inorganic chemistry and uranium (U)recovery. In particular, in alternative embodiments, the inventionprovides processes and methods for the recovery, removal or extractingof, and subsequent purification of uranium from a wet-process phosphoricacid using a continuous ion exchange processing approach, where theuranium is recovered from a phosphoric acid or a phos-acid feedstockusing an ion exchange approach using either a dual or a single cycleextraction methodology.

BACKGROUND

The presence of uranium (U) in wet-process phosphoric acid has been wellestablished and various attempts to recover this valuable material havebeen made over the years. In the mid-1950's various precipitation andsolvent extraction methods were attempted with varying degrees ofsuccess. The discovery of lower cost deposits of uranium in the westernU.S resulted in loss of interest in phos-acid (P₂O₅) as a uranium sourceat that time.

With the subsequent growth in the nuclear power industry and concerns ofpotential uranium supply shortfalls, interest rekindled in the early1970's and as a result several uranium recovery facilities wereconstructed and utilized better solvent extraction methods, primarilybased on the so-called DEPA-TOPO process that was developed at the OakRidge National Laboratory (ORNL). At that time, there was interest inhaving a non-solvent extraction system that would eliminate some of theoperational issues associated with the solvent extraction systems.Unfortunately, there were no continuous contacting systems deemedapplicable to this task, thus solid/liquid contacting techniques werenot investigated to any great extent.

With the subsequent decline in the U₃O₈ from the phos-acid (P₂O₅)industry in the 1990's, there was little commercial-oriented interest inalternate recovery techniques, although some work continued at anacademic and research level. With the resurgence of the uranium industryin the early to mid-2000 decade, opportunities now exist for advancedand/or simplified techniques to recover uranium from this importantsource.

Ion exchange was and continues to be a popular method for uraniumrecovery from more conventional aqueous uranium-containing sources, i.e.copper tailings, leached sandstone ores, etc. The use of fixed bed ionexchange contacting systems has been established in some of theconventional hydrometallurgical industries, such as uranium, and indeedhas proven effective for the recovery of uranium from various sulfateand carbonate solutions.

In the early 1980's a continuous ion exchange system was developed thatwas originally applied to the treatment of solutions containing higherconcentrations of salts or processing requiring the regeneration ofrelatively large quantities of ion exchange resin per unit of processfluid treated. Conventional fixed bed systems have historically hadlimitations when it comes to some of these unique applications. Thedevelopment of the continuous ion exchange system came after the declinein the uranium from phosphoric acid industry. Thus there was littleinterest in the application of this advanced contacting technology tophosphoric acid as a uranium source.

As a result of the resurgence in the demand for uranium from any source,phosphoric acid sources are again being evaluated, especially in lightof growth forecasts of uranium demand outstripping supply over the nextseveral decades. Thus, there is a renewed interest in recovering uraniumand the possibility of applying advance continuous ion exchangetechniques is now an opportunity. A method for uranium recovery fromwet-process phosphoric acid would be beneficial to the industry as aresult of the inherent safety, capital and operating cost advantagesthat would be useful to the phosphoric acid and uranium industries.

SUMMARY

The present invention provides a processes and methods for the recovery,removal or extracting of and subsequent purification of uranium (U) froma wet-process phosphoric acid using a dual or a single extractioncontinuous ion exchange processing approach. Processes and methods ofthe invention comprise dual or a single extraction continuous ionexchange systems that can be operated in a relatively simple,straightforward fashion.

Dual Cycle Uranium Extraction Processes

In alternative embodiments, processes and methods of the inventioncomprise use of a solid contacting media comprising ion exchange resin,e.g., as beads, or equivalent composition or material, to extracturanium (U) from a phosphoric acid source, e.g., a phos-acid (P₂O₅) or aphos-acid feedstock. In alternative embodiments, a modified continuousion exchange contacting system that allows for an effective processextraction is used. In alternative embodiments, the continuous ionexchange contacting system of the invention comprises treatment andextraction methods or processes.

In this exemplary dual cycle ion exchange recovery process of theinvention, solid, ion exchange resin, e.g., as beads, or equivalentcomposition or material, are used to extract the uranium contained inthe phosphoric acid. The treated, low uranium phosphoric acid can bereturned to a phosphoric acid facility. In this exemplary process, aspecific resin is used that extracts (or binds to) uranium from thephosphoric acid source (e.g., phos-acid (P₂O₅), phos-acid feedstock),followed by subsequent stripping, or regeneration, of the uranium (as aneluate) from the resin, or equivalent composition or material, with aseparate stripping (or elution) agent or combination of agents. Anyuranium-binding resin can be used, e.g.: LEWATIT® TP 260™ (Lanxess,Maharashtra, India), a weakly acidic cationic exchange resin withchelating amino methyl phosphonic acid groups for the selective removalof transition heavy metals; AMBERLITE IRC-747™, an aminophosphonicchelating resin (Dow; Rohm & Haas, Philadelphia, Pa.); and S-930™, amacroporous polystyrene based chelating resin, with iminodiacetic groupsdesigned for the removal of cations of heavy metals (Purolite, BalaCynwyd, Pa.); and equivalents thereof.

In this exemplary dual cycle ion exchange recovery process of theinvention, the recovery of uranium from the phosphoric acid source(e.g., phos-acid (P₂O₅), phos-acid feedstock) comprise use of a 2-stageextraction/stripping system, where the stripping or regenerationsolution for the primary circuit is further treated and processed in asecondary cycle to recover a concentrated a uranyl solution for feed tothe uranium refining section, e.g., as illustrated in FIG. 1.

In alternative embodiments, the phos-acid is first pretreated with afiltering or clarification aids to remove all or substantially allsuspended solids from the solution, along with a slight degree ofdissolved color-bodies. In alternative embodiments comprising use of ionexchange approaches, the degree of color body removal required issignificantly less than is associated with solvent extraction systems,thus the pretreatment needs for the phos-acid, prior to uranium (U)recovery, are considerably reduced and simplified with the use of thecontinuous ion exchange approach.

The invention provides processes and methods for the isolation,extraction or recovery of a uranium or a uranium oxide from awet-process phosphoric acid using a continuous ion exchange system,comprising:

(a) providing a phosphoric acid solution, or a solution comprising aphosphoric acid, or a phos-acid feedstock, comprising a uranium or auranium oxide,

wherein optionally the phosphoric acid streams with P₂O₅ concentrationsranging from about 1% to about 60% P₂O₅/weight, or between about 20% andabout 57% P₂O₅/weight;

(b) providing a continuous ion exchange system comprising a resin or anequivalent material or composition capable of binding the uranium or auranium oxide (also called “a complexing resin”),

wherein optionally the resin or material comprises or is:

-   -   LEWATIT® TP 260™ (Lanxess, Maharashtra, India), a weakly acidic        cationic exchange resin with chelating amino methyl phosphonic        acid groups for the selective removal of transition heavy        metals, or equivalent;    -   AMBERLITE IRC-747™, an aminophosphonic chelating resin. or        equivalent (Dow (Midland, Mich.); Rohm & Haas, Philadelphia,        Pa.);    -   PUROLITE S-930™, a macroporous polystyrene based chelating        resin, with iminodiacetic groups designed for the removal of        cations of heavy metals, or equivalent (Purolite, Bala Cynwyd,        Pa.);    -   a resin, composition or a material, or a non-resin solid or a        semi-solid material, comprising chelating groups,        functionalities or moieties that can bind uranium (U) and that        comprise iminodiacetic groups, chelating aminomethyl phosphonic        acid groups or aminophosphonic groups, or similar chelating        functionalities or moieties, wherein optionally the compositions        comprise beads, wires, meshes, nanobeads, nanotubes, nanowires        or other nano-structures, or hydrogels.

(c) treating or pre-treating, or filtering, the phosphoric acidsolution, solution comprising a phosphoric acid or a phos-acid feedstockwith a clarification process or a filtering process, or a clarificationaid,

wherein optionally the clarification process, filtering process orclarification aid comprises an activated clay, an activated carbon, anactivated silica, or equivalents or similar clarification material, orany combination thereof;

(d) applying the treated, pre-treated, or clarified solution orphosphoric acid solution or phos-acid feedstock of (c) to the resin, orother chelating material or composition of (b), under conditions thatcause the uranium (U) to remain on or bind to the resin or material,

wherein optionally an effluent is produced that is substantially free ofthe uranium (U), and substantially most of the uranium (U) remains boundto the complexing (or chelating) exchange resin,

and optionally the complexing resin is used to remove the uranium (U)from the phos-acid and load the uranium (U) onto the selected complexingion exchange resin; and

(e) recovering the uranium (U) from the resin, or other chelatingmaterial or composition, by treating the uranium-loaded resin with analkali solution to neutralize the free acidity in the resin or otherchelating material; followed by regenerating the resin or chelatingmaterial using an alkali carbonate solution or equivalent, optionally anammonium carbonate, a sodium carbonate, or a potassium carbonate, at apH that is greater than about 9.0, or greater than about 9.1, 9.2, 9.4,9.4 or 9.5, to produce a “primary loaded regeneration solution”;

and optionally alkali concentrations range from 0.5 molar to 3 molar, orbetween 1 and 2 molar.

In alternative embodiments, the regeneration of the uranium-loadedresin, or other chelating material or composition, comprises contactingthe loaded resin, or other chelating material or composition, with asolution of alkali carbonate, or equivalent, optionally an ammoniumcarbonate, a sodium carbonate, or a potassium carbonate, to convert theuranium to an anionic carbonate complex, which has no affinity for thechelating, or other chelating material or composition, and producing anintermediate primary regeneration solution that is smaller in volume,when compared to the primary phosphoric acid flow, and which alsocontains a higher concentration of uranium in the solution phase.

In alternative embodiments, the processes and methods of the inventionfurther comprise washing the regenerated resin, or other chelatingmaterial or composition, (from which the uranium (U) has been released,or eluted) with a water, or slightly acidic solution to remove anyentrained alkali in the intermediate regeneration solution from theresin, or other chelating material or composition, prior to its reentryinto the uranium extraction stage of the continuous ion exchange system.

In alternative embodiments, the processes and methods of the inventionfurther comprise treating the intermediate primary regeneration solutionin a second continuous ion exchange system comprising an anion exchangeresin or equivalent material or composition, wherein the solution iscontacted with the anion exchange resin or equivalent material orcomposition, and the anion uranium complex is removed from theintermediate primary regeneration solution as an anionic complex.

In alternative embodiments, the processes and methods of the inventionfurther comprise treating the anionic resin, or equivalent compositionor material, that has been loaded with the uranium with a water solutionto remove the entrained intermediate primary solution from the resin, orequivalent composition or material.

In alternative embodiments, the processes and methods of the inventionfurther comprise treating the washed secondary cycle anionic resin, orequivalent composition or material, with an acidic solution (the“secondary regeneration solution”) to remove the uranium from the resin,or equivalent composition or material, by converting the uranium complexto a cationic form which has little affinity for the anion exchangeresin, or equivalent composition or material, wherein optionally theacid solution comprises a weak sulfuric acid, nitric acid, hydrochloricacid or equivalent solution.

In alternative embodiments, the initial contacting of the resin, orequivalent composition or material, with the acid solution is carriedout in an up-flow operational mode and results in the decomposition ofany residual carbonate solution in the ion exchange resin, or equivalentcomposition or material, and assists in the expansion of the resin bed,with the resulting production of an acidic uranium-containing secondaryloaded regeneration solution.

In alternative embodiments, the processes and methods of the inventionfurther comprise the treatment of the regenerated resin, or equivalentcomposition or material, from the secondary regeneration stage withwater to remove entrained acidic regeneration solution.

In alternative embodiments, the processes and methods of the inventionfurther comprise post-treating the anionic resin, or equivalentcomposition or material, with an alkali solution to neutralize anyresidual acidity in the resin, or equivalent composition or material,prior to its reentry into the secondary uranium extraction zone wherethe resin, or equivalent composition or material, is contacted withincoming primary cycle loaded ammonium uranyl-tricarbonate solutionwhich contains the uranium recovered from the primary cycle, in order tominimize any neutralization of the carbonate solution in the secondaryextraction stages, and optionally further comprising treating theuranium-loaded secondary regeneration solution with an alkali solutionto raise the pH of the solution to between about pH 2.5 to about pH 7,or to between about pH 3.5 to about pH 6, and optionally the alkalisolution comprises an alkali hydroxide, optionally an ammoniumhydroxide, a sodium hydroxide or equivalents, at concentrations rangingfrom 10% to about 30%; and optionally the alkali solutions willgenerally have pH's greater than pH 10 in their solution form.

In alternative embodiments, the processes and methods of the inventionfurther comprise the addition of a hydrogen peroxide to the pH adjustedsolution in an amount sufficient to form a uranyl peroxide compound andallow for excess peroxide to be present in the solution to ensurecomplete uranyl peroxide precipitation.

In alternative embodiments, the processes and methods of the inventionfurther comprise the separation of the uranyl peroxide precipitate fromthe solution phase, optionally utilizing: settling; filtration,centrifugation, and equivalents, then washing the solids with water in aconventional approach, optionally comprising washing the solids on afilter; or repulping of the solids with water, followed by settling orfiltration or centrifugation or equivalents, and optionally furthercomprising additional washing of the uranyl peroxide with water toremove the bulk of any entrained secondary solution (uranium-free) viaadditional filter washing; and optionally washing within a centrifuge oradditional repulping with water followed by settling.

In alternative embodiments, the processes and methods of the inventionfurther comprise drying the uranyl peroxide to form a dry solidmaterial, and optionally the dry uranyl peroxide is further heated to atemperature sufficient to decompose or calcine (e.g., heating to a hightemperature but below the melting or fusing point, causing loss ofmoisture, reduction or oxidation, and the decomposition of carbonatesand other compounds) the uranyl peroxide and form a uranium oxidecompound (U₃O₈).

Single Cycle Uranium Extraction Processes

In alternative embodiments of the “single cycle” exemplary method of theinvention, a solid contacting media, such as ion exchange resin beads,are used to extract uranium (U) from a phosphoric acid source, e.g., aphos-acid (P₂O₅) or a phos-acid feedstock. In alternative embodiments, amodified continuous ion exchange contacting system is used that providesan effective process extraction and treatment methodology when comparedto non-continuous systems, and provides the ability to produce anammonium uranyl tricarbonate solution from a single extraction step.

In alternative embodiments of the ion exchange recovery process of theinvention, solid, ion exchange resin beads, or equivalent materials, areused to extract the uranium contained in the phosphoric acid source. Thetreated (low uranium phosphoric acid) can be returned to the phosphoricacid facility.

In alternative embodiments, the invention provides a U₃O₈ recoverysystem from a phos-acid source comprising use of a specific resin orequivalent material that can extract uranium (U) from the phosphoricacid source, e.g., a phos-acid (P₂O₅) or a phos-acid feedstock, withsubsequent regeneration of the resin with a separate regeneration agentor combination of agents. Specialized resins or equivalent materials, asdescribed herein, are used for this purpose, and the extent of resinsand equivalent materials available for unique applications has increasedconsiderably over the past 15 to 20 years. This advancement in theavailability of resin and equivalent materials has also been spurred bythe development and availability of continuous contacting systems thatallow for more efficient contacting and operability.

In alternative embodiments of the invention's continuous processes forthe recovery of uranium (U) from a phos-acid (P₂O₅), a single stageextraction/regeneration system is used where the regeneration solutionfor the primary circuit is heated to decompose the excess ammoniumcarbonate in the solution; lower the pH; then subsequently precipitatethe uranium as an ammonium uranyl carbonate material. This precipitateis digested in an acid solution, such as sulfuric acid, and thensubsequently refined via the pH adjustment of the solution to about 3 toabout 5, followed by treatment of the partially neutralized solutionwith hydrogen peroxide or equivalent to precipitate a uranyl peroxidematerial, finally followed by drying and calcining to produce a uraniumoxide product.

In alternative embodiments, the phos-acid is first pretreated with afilter, clarification aid, or equivalent, to assist in the removal ofsuspended solids from the solution, along with a slight degree ofdissolved color-body material. In the case of solvent extraction, or theso-called “2nd Generation” systems, there may be a need for asignificant degree of dissolved organic (color body) removal due to thepotential for emulsion formation within the solvent extraction systemitself. For the ion exchange processes of this invention, the degree ofcolor body removal required may be significantly less than with thesolvent extraction systems, thus the pretreatment needs for thephos-acid, prior to uranium (U) recovery, are considerably reduced andsimplified.

The invention provides processes and methods for the isolation,extraction or recovery of a uranium or a uranium oxide from awet-process phosphoric acid using a continuous ion exchange systemcomprising:

(a) providing a phosphoric acid solution, or a solution comprising aphosphoric acid, or a phos-acid feedstock, comprising a uranium or auranium oxide,

wherein optionally the phosphoric acid streams with P₂O₅ concentrationsranging from about 1% to about 60% P₂O₅/weight, or between about 20% andabout 57% P₂O₅/weight;

(b) providing a continuous ion exchange system comprising a resin or amaterial capable of binding the uranium or a uranium oxide (also called“a complexing resin”),

wherein optionally the resin or a material comprises or is:

-   -   LEWATIT® TP 260™ (Lanxess, Maharashtra, India), a weakly acidic        cationic exchange resin with chelating amino methyl phosphonic        acid groups for the selective removal of transition heavy        metals;    -   AMBERLITE IRC-747™, an aminophosphonic chelating resin (Dow;        Rohm & Haas, Philadelphia, Pa.);    -   S-930™, a macroporous polystyrene based chelating resin, with        iminodiacetic groups designed for the removal of cations of        heavy metals (Purolite, Bala Cynwyd, Pa.);    -   a resin, composition or a material, or a non-resin solid or a        semi-solid material, comprising chelating groups,        functionalities or moieties that can bind uranium (U) and that        comprise iminodiacetic groups, chelating aminomethyl phosphonic        acid groups or aminophosphonic groups, or similar chelating        functionalities or moieties, wherein optionally the compositions        comprise beads, wires, meshes, nanobeads, nanotubes, nanowires        or other nano-structures, or hydrogels.

(c) treating or pre-treating, or filtering, the phosphoric acidsolution, solution comprising a phosphoric acid or phos-acid feedstockwith a clarification process or a filtering process, or a clarificationaid,

wherein optionally the clarification process, filtering process orclarification aid comprises an activated clay, an activated carbon, anactivated silica, or equivalents or similar clarification material, orany combination thereof;

(d) applying the treated, pre-treated, or clarified solution orphosphoric acid solution or phos-acid feedstock of (c) to the resin, orother chelating material or composition of (b), under conditions thatcauses the uranium (U) to remain on or bind to the resin or material,

wherein optionally an effluent is produced that is substantially free ofthe uranium (U), and substantially most of the uranium (U) remains boundto the complexing (or chelating) exchange resin, and optionally thecomplexing resin, or other chelating material or composition, is used toremove the uranium (U) from the phos-acid and load the uranium (U) ontothe selected complexing ion exchange resin;

(e) pretreatment of the loaded chelating resin, or other chelatingmaterial or composition, with an alkali solution, optionally an ammoniumhydroxide, a sodium hydroxide or equivalent, to neutralize any freeacidity in the resin prior to actual regeneration of the resin in theregeneration zone (where the resin is contacted with an alkali carbonatesolution); and

(f) recovering the uranium (U) from the resin, or other chelatingmaterial or composition (or regeneration of the uranium-loaded resin, orother chelating material or composition), by treating the uranium-loadedresin, or other chelating material or composition, with a solution ofalkali carbonate or equivalent, to convert the uranium to an anioniccarbonate complex which has no affinity for the chelating resin, or theother chelating material or composition, and producing an intermediateprimary regeneration solution, which is the same as the primaryregeneration solution produced in the first cycle of the dual cycleapproach, that is smaller in volume, when compared to the primaryphosphoric acid (treated, pre-treated, or clarified solution phosphoricacid solution or phos-acid feedstock) flow, and also contains a higherconcentration of uranium in the solution phase.

In alternative embodiments, the alkali solution used in the pretreatmentstep comprises a portion of the regeneration solution exiting theprimary regeneration zone, which is then used to neutralize any freeacidity in the resin, or other chelating material or composition, priorto actual resin, or other chelating material or composition,regeneration, wherein with resin, or other chelating material orcomposition, neutralization any uranium contained in the portion of theregeneration solution used for pretreatment is reloaded onto the resin,or other chelating material or composition, due to the decrease in pHthat takes place in the pretreatment stage by virtue of the ammoniumcarbonate, or equivalent, reacting with traces of entrained acid.

In alternative embodiments, the regenerated resin, or other chelatingmaterial or composition, is washed with water, or a slightly acidicsolution, to remove any entrained alkali regeneration solution from theresin prior to its reentry into the uranium extraction stage of thecontinuous ion exchange system.

In alternative embodiments, the processes and methods of the inventionfurther comprise concentration of the intermediate primary regenerationsolution (optionally an ammonium uranyl-tricarbonate) in an evaporationunit to reduce the water content and decompose excess alkali carbonateto form bicarbonates and reduce the pH of the solution, resulting in theprecipitation of an ammonium uranyl carbonate/oxide material, optionallycomprising a uranyl carbonate/oxide filter cake.

In alternative embodiments, the processes and methods of the inventionfurther comprise filtering the uranyl carbonate/oxide precipitate, andthen washing the precipitate with a small amount of water to remove theexcess alkali carbonate or an entrained carbonate/bicarbonate solutionfrom the uranyl carbonate/oxide filter cake.

In alternative embodiments, the processes and methods of the inventionfurther comprise recovering the ammonia evolved in the decomposition ofthe excess alkali carbonate with a separate water stream, or with thefiltrate, and recycling of the resulting solution to the primary ionexchange system.

In alternative embodiments, the processes and methods of the inventionfurther comprise digestion of the uranyl carbonate/oxide filter cakewith an acid solution to produce an acidic, soluble ammonium uranyl saltsolution; wherein optionally the acid solution comprises a sulfuricacid, a nitric acid, a hydrochloric acid or an equivalent.

In alternative embodiments, the processes and methods of the inventionfurther comprise treating the soluble ammonium uranyl salt solution withan alkali solution to raise the pH of the solution to between about pH2.5 to about pH 7, or to between about pH 3.5 to about pH 6, andoptionally the alkali solution comprises an alkali hydroxide, e.g.ammonium hydroxide, sodium hydroxide and the like at concentrationsranging from 10% to about 30%, wherein optionally the alkali solutionshave pH's greater than about pH 10 in their solution form.

In alternative embodiments, the processes and methods of the inventionfurther comprise adding hydrogen peroxide to the pH adjusted solution inan amount sufficient to form a uranyl peroxide compound and allow forexcess peroxide to be present in the solution to ensure complete uranylperoxide precipitation.

In alternative embodiments, the processes and methods of the inventionfurther comprise the separation of the uranyl peroxide precipitate fromthe solution phase, optionally utilizing settling; filtration,centrifugation, or equivalents, then washing the solids with water,optionally washing comprising a washing the solids on a filter, oroptionally repulping of the solids with water, followed by settling orfiltration or centrifugation or equivalents, and optionally furthercomprising additional washing of the uranyl peroxide with water toremove the bulk of any entrained secondary solution (uranium-free) viaadditional filter washing; optionally washing within a centrifuge; oroptionally additional repulping with water followed by settling.

In alternative embodiments, the processes and methods of the inventionfurther comprise drying the uranyl peroxide to form a dry solidmaterial, and optionally the dry uranyl peroxide is further heated to atemperature sufficient to decompose, or calcine, the uranyl peroxide andform a uranium oxide compound (U₃O₈).

The invention provides industrial processes for the isolation,extraction or recovery of uranium from a wet-process phosphoric acidusing a continuous ion exchange system, or for isolation, extraction orrecovery of a uranium oxide compound (U₃O₈), or a uranium (U),comprising an industrial process as set forth in FIG. 1, or FIG. 2, orany portion or sub-process thereof, wherein optionally the uranium oxidecompound (U₃O₈), or a uranium (U) is extracted, isolated or recoveredfrom a sample, wherein optionally the sample comprises an ore or amineral ore, or a uraninite (UO₂) or a pitchblende (UO₃, U₂O₅), agummite, an autunite, a saleeite, a torbernite, a hydrated uraniumsilicate, a coffinite, a uranophane or a sklodowskite.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

All publications, patents, patent applications cited herein are herebyexpressly incorporated by reference for all purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings set forth herein are illustrative of embodiments of theinvention and are not meant to limit the scope of the invention asencompassed by the claims.

Figures are described and discussed herein.

FIG. 1 schematically illustrates an exemplary “dual cycle” process ofthe invention, an overall process flow diagram for this exemplary “dualcycle” uranium extraction or recovery process from a phosphoric acidsolution, or a solution comprising a phosphoric acid, or a phos-acidfeedstock, using ion exchange resins.

FIG. 2 schematically illustrates an exemplary “single cycle” process ofthe invention, an overall process flow diagram for this exemplary“single cycle” uranium extraction or recovery process from a phosphoricacid solution, or a solution comprising a phosphoric acid, or aphos-acid feedstock, using ion exchange resins.

Like reference symbols in the various drawings indicate like elements.

Reference will now be made in detail to various exemplary embodiments ofthe invention, examples of which are illustrated in the accompanyingdrawings. The following detailed description is provided to give thereader a better understanding of certain details of aspects andembodiments of the invention, and should not be interpreted as alimitation on the scope of the invention.

DETAILED DESCRIPTION

In alternative embodiments, the invention provides processes and methodsfor the recovery, removal or extracting of, and subsequent purificationof uranium from a wet-process phosphoric acid using a continuous ionexchange processing approach, using either a dual or a single extractionprocess methodology.

Dual Cycle Uranium Extraction Processes

In alternative embodiments, an exemplary “dual cycle” process for theion exchange route for uranium recovery and purification is shown inFIG. 1. In FIG. 1, the basic process blocks are shown along with themajor material inputs and outputs. Stream numbers for the descriptionare noted as follows (stream#):

In alternative embodiments, an exemplary “dual cycle” process for theion exchange route for uranium recovery and purification is divided intofour major areas:

-   -   Phosphoric Acid Pretreatment, which can comprise acid cooling        (which for the continuous ion exchange system is generally not        required, and in exemplary embodiments is not included, but is        shown in the Figure for completeness), and acid clarification;    -   Primary Ion Exchange Extraction and Regeneration System, which        contains the primary continuous ion exchange system along with        the systems required for preparation of the primary pretreatment        and regeneration solutions, and the normally associated        peripheries, e.g. surge tanks, etc;    -   Secondary Ion Exchange Extraction and Regeneration System and        the support systems required for secondary regeneration solution        preparation and handling;    -   Uranium (U) Precipitation Circuit, where the secondary U-loaded        regeneration solution is pH adjusted and the soluble U        precipitated as an insoluble uranyl peroxide material; and,    -   Uranium Washing and Drying-Calcining, comprising one or more        uranyl peroxide solid washing steps along with subsequent uranyl        peroxide drying and calcining to produce a U₃O₈ oxide material.        Exemplary processes of the invention can also comprise uranium        packaging and/or storage steps (not shown in FIG. 1); these are        standard operations.        Phosphoric Acid Pretreatment:

In alternative embodiments, the acid preparation for the ion exchangeapproach comprises reducing the suspended solids in a feed acid (e.g., aphos-acid feedstock) to a specific target level, typically to a value ofless than about 1,000 ppm suspended solids by weight. It is important tonote that some level of solids is tolerable in the continuous contactingsystem, unlike fixed bed systems, since there is a routine, andsometimes frequent, “cleaning” step within the exemplary continuous ionexchange operation itself.

In alternative embodiments, the incoming phos-acid (1) is cooled, andthen treated with a filtering or a clarification aid (2) for suspendedsolids removal and minor color-body removal, followed by clarification.The solids from this step (3) can be returned to the phos-acid facility.For solvent extraction systems, acid cooling is generally required dueto vapor pressure, flammability, and extraction efficiency issues. Ithas been determined that with the processes of this invention, includingexemplary continuous ion exchange approaches of this invention, theextent of acid cooling is not as great and in many cases is not requiredat all (depending on specific plant situations).

In alternative embodiments, a primary difference between this exemplary“dual cycle” approach and previous solvent extraction methodologies isthat when practicing processes of this invention a solid, polymeric,functionalized material, i.e., a resin, is used to extract the uranium(U) from the phos-acid media or source, e.g., a phos-acid feedstock. Inalternative embodiments of exemplary processes of this invention, noliquid extractants and diluent solvents, e.g. high grade kerosene, areused; thus, issues with emulsion formation are essentially eliminated.

Primary Ion Exchange Extraction/Regeneration:

In alternative embodiments, the pretreated (filtered or clarified)phos-acid (4) enters the Primary Continuous Contacting System where itis contacted in a continuous unit with the chosen ion exchange resinmaterial, or equivalent alternative material or composition. Inalternative embodiments of the contacting systems, the acid passesthrough the resin material, or equivalent alternative material orcomposition, where the contained uranium (soluble) is transferred fromthe phosphoric acid to the resin (or equivalent) matrix itself via aspecific ion exchange mechanism. The uranium (U) is in a cationic formwhen it is extracted. The low uranium acid (5) is then returned toplant.

In alternative embodiments, the resin, or equivalent alternativematerial or composition, removes the uranium (U) from the acid in acationic form. Any uranium (U) chelating material can be used; forexample, resins that can be used to practice this invention comprise:

-   -   LEWATIT® TP 260™ (Lanxess, Maharashtra, India), a weakly acidic        cationic exchange resin with chelating amino methyl phosphonic        acid groups for the selective removal of transition heavy        metals;    -   AMBERLITE IRC-747™, an aminophosphonic chelating resin (Dow;        Rohm & Haas, Philadelphia, Pa.);    -   S-930™, a macroporous polystyrene based chelating resin, with        iminodiacetic groups designed for the removal of cations of        heavy metals (Purolite, Bala Cynwyd, Pa.); and,    -   equivalents thereof.

In alternative embodiments, the resin, or equivalent alternativematerial or composition, that removes the uranium (U) from the acid in acationic form comprises a resin, a composition or a material, or anon-resin solid or a semi-solid material, comprising chelating groups,functionalities or moieties that can bind uranium (U) and that compriseiminodiacetic groups, chelating aminomethyl phosphonic acid groups oraminophosphonic groups, or similar chelating functionalities ormoieties, wherein optionally the compositions comprise beads, wires,meshes, nanobeads, nanotubes, nanowires or other nano-structures, orhydrogels.

These resins are listed for example purposes and in no way limits theuse of other similar types of materials, including non-resin solid orsemi-solid materials, that can similarly bind uranium (U) and beextracted (eluted) from the material as described herein. For example,beads, wires, meshes, nanobeads, nanotubes, nanowires or othernano-structures, or hydrogels and the like, comprising iminodiaceticgroups, chelating aminomethyl phosphonic acid groups or aminophosphonicgroups, or similar chelating functionalities or moieties, can be used.

In alternative embodiments, in the case of ion exchange, there is noneed for additional post treatment since the extraction media (i.e., theresin or equivalent materials) have no solubility in the phos-acid,P₂O₅. In alternative embodiments, uranium contained in the resin is thenremoved in the regeneration portion or step of this exemplary process ofthe invention.

In alternative embodiments, the loaded resin from the primary contactingstep is washed with a small amount of water (6), which is internallycontained, then transfers into the primary pretreatment stage of thecontacting system. Within this portion of the continuous contactingsystem the uranium (U)-loaded resin is contacted with an alkali solution(7) to prepare the resin for regeneration. The spent pretreatmentsolution (8) is returned to the phos-acid plant waste water systems orcan be used as make-up water in the phos-acid, P₂O₅ plant fertilizeroperations.

In alternative embodiments, the pretreatment step uses a weak alkalisolution, such as ammonium hydroxide, to neutralize any residual acidvalue in the resin. This can be critical in situations where the resinenters the regeneration stage and there is no residual acid value thatcould react with the ammonium carbonate solution and reduce its pH.

It has also been discovered that by operating a portion of thepretreatment stage in an up-flow mode the resin beds can be expandedduring each cycle. This expansion allows for regular cleaning of theresin and enables the continuous ion exchange system to handle a muchhigher level of solids than either fixed bed systems or alternativesolvent extraction systems. Any solids accumulated in the system arethen flushed from the resin and transferred to the spent pretreatmentsolution storage area, then eventually the solids can be disposed of,e.g., to a phos-acid plant's waste solids systems.

In alternative embodiments, the pretreated resin is next contacted withan alkali carbonate solution (9) to remove (e.g., elute) the uraniumfrom the resin and return the resin to its “extraction” form. In thisstep the alkali carbonate solution converts the uranium to an anioniccomplex that has no affinity for the ion exchange resin. The uraniumthus transfers from the resin phase to the alkali solution phase. Theresulting loaded primary regeneration solution (10) is then transferredto the secondary ion exchange processing system. Suitable carbonatesolutions include ammonium carbonate, sodium carbonate, potassiumcarbonate, and the like. The choice of the appropriate solution willtypically be plant specific.

In alternative embodiments, it may be critical that the pH in theregeneration stage be above a minimum value. In alternative embodimentsthe pH of the regeneration solution containing the uranium removed fromthe resin is above about pH 9.0, or above about pH 9.1, pH 9.2, pH 9.3,pH 9.4, pH 9.5 or pH 9.6 or more. If the pH falls below certain levelsthe uranium in the regeneration solution can reload onto the resin.While there is no upper pH limit, in alternative embodiments, theammonium carbonate solution with some slight addition of ammonia has apH in the range of about pH 9.8 to about pH 10.2, 10.3, 10.4 or 10.5,which is acceptable for this process.

Secondary Ion Exchange Extraction/Regeneration Systems:

In alternative embodiments of the exemplary secondary extraction andregeneration systems of this invention, the loaded primary regenerationsolution (10), for example, an alkali carbonate solution or equivalent,is contacted in a secondary ion exchange system. The secondary ionexchange system can be considerably smaller than the primary circuit anddifferent ion exchange resins are used, however the principle ofoperation is similar to that used in the primary extraction system.

In alternative embodiments, the uranium (U) contained in the loadedprimary regeneration solution is transferred to the secondary resin, orequivalent material or composition, comprising an anion material, thusit has a high affinity for the uranium complex in the ammonium carbonatesolution. In alternative embodiments, the lean, primary regenerationsolution from the secondary system (11) is recycled to the maximumextent possible. In alternative embodiments, the secondary resin, orequivalent material or composition, comprises:

-   -   a LEWATIT® K 6267™ (Lanxess, Maharashtra, India), or equivalent;    -   PUROLITE A-600™, having a functional group comprising a Type 1        quaternary ammonium (Purolite, Bala Cynwyd, PA), or equivalent;    -   any resin, or equivalent material or composition having a high        affinity for the uranium complex, e.g., having a functional        group comprising a Type 1 quaternary ammonium, or equivalents.

In alternative embodiments, the loaded secondary resin, or equivalentmaterial or composition, is then subjected to a water washing step (12),followed by contacting with a secondary regeneration solution (13) thatis acidic, e.g. a weak sulfuric acid, nitric acid, hydrochloric acid orequivalent solution. Neutral salt solutions such as ammonium nitrate;ammonium chloride; sodium chloride; sodium nitrate; and the like canalso be used, but the acids are generally preferred, especiallysulfuric, due to its compatibility with the existing phos-acidoperations. The secondary loaded regeneration solution (14), nowcontaining a high concentration of U, is then transferred to the Uprecipitation system.

In alternative embodiments, use of an acidic solution, including but notlimited to weak sulfuric acid, nitric acid, hydrochloric acid and thelike, enhances the secondary regeneration by ensuring that all of theuranium is reconverted to a cationic form, which has no affinity for theanionic resin, or equivalent material or composition.

Before this invention, there was some concern about the use of a low pHsolution for the regeneration of the anionic resins, since any residualcarbonate solution remaining in the resin after the secondary loadingwould react with the acid and decompose to form an ammonium salt (e.g.ammonium sulfate) and release carbon dioxide within the resin bed.However, to address this concern, it has been discovered that bypracticing a continuous ion exchange approach of this invention, aportion of the regeneration zone can be operated in an up-flow mode; andby operating the initial regeneration contact in this mode there is somelevel of decomposition and the released CO₂ actually assists in theexpansion of the resin bed and allows for a level of resin cleaning atthe beginning of the regeneration stage.

In alternative embodiments, processes of the invention comprise use ofup-flow operations in the ion exchange system. In alternativeembodiments, continuous ion exchange systems comprise use of up-flowzones which can be operated with or without the assistance of an airscour to assist the up-flowing liquid in expanding the resin bed andloosening any accumulated solids so they can be flushed from the resin.In alternative embodiments, in the case of the second cycle situation,the release of CO₂ within the resin bed allows for “in-situ” gasformation and subsequent resin bed scouring.

Secondary Loaded Regeneration Solution Precipitation:

In alternative embodiments, in the precipitation step, the secondaryloaded regeneration solution (14) is combined with an alkali solution,such as ammonium hydroxide, to increase the pH of the secondaryregeneration solution to about pH 2.5 to about pH 7.0; or to betweenabout pH 3.5 to about pH 6. After the pH adjustment, a precipitatingagent (16), for example, a hydrogen peroxide or equivalent, is added anda uranyl peroxide precipitate is formed. In alternative embodiments theperoxide slurry is then transferred to the decantation, washing andcalcining operation.

Precipitated Uranium Washing/Calcining:

In alternative embodiments, as the uranyl peroxide slurry (17) entersthis process step, a small amount of pH adjustment reagent (18) can beis added to adjust the pH of the slurry. If the pH of the slurry is low,then an alkali solution, such as ammonium hydroxide or equivalent, canbe used for the adjustment. If the slurry is too alkali, i.e. pH toohigh, then a small amount of acid can be added, e.g. H₂SO₄, orequivalent. This mixture is then clarified and the thickened uranylperoxide sludge washed with a small amount of water (19).

In alternative embodiments, the washed uranyl peroxide solids (UO₄.2H₂O)are then centrifuged and the recovered solids transferred to adryer/calciner system where the uranyl peroxide is decomposed to producea uranium oxide product (21). The centrate solution is also collectedand is filtered. In alternative embodiments some of the spent solutionsare recycled to up-stream processes to minimize the overall plantaqueous spent solution volume (20).

In alternative embodiments, the calcined oxide product (U₃O₈) is lightlymilled then surged and loaded into drums for storage and shipment. Acontained drum loading system can be used to minimize the potential fordust emission.

Single Cycle Uranium Extraction Processes

In alternative embodiments, an exemplary “single cycle” process for theion exchange route uranium recovery and purification is shown in FIG. 2.In FIG. 2, the basic process blocks are shown along with the majormaterial inputs and outputs. Stream numbers for the description arenoted as follows (stream#):

In alternative embodiments, the exemplary “single cycle” process isdivided into several major areas:

-   -   Phosphoric Acid Pretreatment, comprising acid cooling, and        filtering or clarification;    -   Primary Ion Exchange Extraction and Regeneration System,        comprising or containing the primary continuous ion exchange        system, along with the systems required for preparation of the        primary pretreatment and regeneration solutions and the normally        associated peripheries, e.g. surge tanks, etc;    -   Primary Regeneration Solution Evaporation and the support        systems required for concentrating the primary regeneration        solution and reducing the pH by excess ammonium carbonate        decomposition;    -   Uranyl Precipitate Filtration/Washing/Digestion where the        precipitated uranyl material is filtered, washed, then digested        with an acid solution to dissolve the uranyl compound and        produce an acidic ammonium uranyl salt (soluble);    -   Uranium Precipitation Circuit wherein the acidic ammonium uranyl        salt solution is pH adjusted and the soluble uranium (U)        precipitated as an insoluble uranyl peroxide material; and    -   Uranium Washing and Drying-Calcining, comprising uranyl peroxide        solids washing steps along with subsequent uranium (U) drying        and calcining to produce a U₃O₈ oxide material.

Exemplary processes of the invention can also comprise uranium packagingand/or storage steps (not shown in FIG. 2); these are standardoperations.

Phosphoric Acid Pretreatment:

In alternative embodiments, the acid preparation for the ion exchangeapproach comprises reducing the suspended solids in a feed acid (e.g., aphos-acid feedstock) to a specific target level or less than about 1,000ppm. It is important to note that some level of solids is tolerable inthe continuous contacting system, unlike fixed bed ion exchange orsolvent extraction systems, since there is a routine, and sometimesfrequent, “cleaning” step within the exemplary ion exchange operationitself.

In alternative embodiments, the incoming phos-acid (1) may be cooled andthen treated with a clarification aid (2) for suspended solids removaland minor color-body removal, followed by clarification. The solids fromthis step (3) can be returned to the phos-acid facility. As in the dualcycle case, In alternative embodiments the cooling system may not berequired for the operation and will be site specific.

In alternative embodiments, a primary difference between this exemplaryprocess of the invention and previous solvent extraction methodologiesis that in this exemplary process of the invention, a solid, polymeric,functionalized material is used to extract the uranium (U) from thephos-acid media. No liquid extractants and diluent solvents, e.g. highgrade kerosene, are used in this invention's process, thus issues withemulsion formation and fire/explosion risk are essentially eliminated.As indicated in the dual cycle discussion, in alternative embodimentsthe elimination of the need for organic diluents, such as kerosene, alsoeliminates the potential for downstream damage in the existing P₂O₅operations that would result from entrained solvent materials.

Primary Ion Exchange Extraction/Regeneration:

In alternative embodiments, the filtered or clarified pretreatedphos-acid or phos-acid feedstock (4) enters the Primary ContinuousContacting System wherein it is contacted in a continuous unit with thechosen ion exchange resin or equivalent material or composition. Inalternative embodiments the acid passes through the resin material, orequivalent material or composition, where the contained uranium(soluble) is transferred from the phosphoric acid to the resin matrix,or equivalent material or composition, itself via a specific ionexchange mechanism, and the uranium (U) is in the cationic form when itis extracted. The low uranium acid (5) can then returned to plant. Inalternative embodiments, the resin, or equivalent material orcomposition, removes the uranium (U) from the acid in a cationic form.Any uranium (U) chelating material can be used; for example, resins, orequivalent materials or compositions, that can be used to practice thisinvention comprise:

-   -   LEWATIT® TP 260™ (Lanxess, Maharashtra, India), a weakly acidic        cationic exchange resin with chelating amino methyl phosphonic        acid groups for the selective removal of transition heavy        metals, or equivalents thereof;    -   AMBERLITE IRC-747™, an aminophosphonic chelating resin (Dow;        Rohm & Haas, Philadelphia, Pa.), or equivalents thereof;    -   S-930™, a macroporous polystyrene based chelating resin, with        iminodiacetic groups designed for the removal of cations of        heavy metals (Purolite, Bala Cynwyd, Pa.), or equivalents        thereof; and,    -   a resin, composition or a material, or a non-resin solid or a        semi-solid material, comprising chelating groups,        functionalities or moieties that can bind uranium (U) and that        comprise iminodiacetic groups, chelating aminomethyl phosphonic        acid groups or aminophosphonic groups, or similar chelating        functionalities or moieties, wherein optionally the compositions        comprise beads, wires, meshes, nanobeads, nanotubes, nanowires        or other nano-structures, or hydrogels.

These resins, or equivalent materials or compositions, are listed forexample purposes and in no way limits the use of other similar types ofmaterials, including non-resin solid or semi-solid materials, that cansimilarly bind uranium (U) and be extracted (eluted) from the materialas described herein. For example, beads, wires, meshes, nanobeads,nanotubes, nanowires or other nano-structures, or hydrogels and thelike, comprising iminodiacetic groups, chelating aminomethyl phosphonicacid groups or aminophosphonic groups, or similar chelatingfunctionalities or moieties, can be used.

In alternative embodiments, when practicing an ion exchange process ofthis invention, there is no need for additional post treatment, sincethe extraction media (i.e. resin or equivalent compositions ormaterials) has no solubility in the P₂O₅ (in earlier solvent extractionsystems, post-treatment of the phos-acid was of paramount importancesince the contained solvent, unless removed to extremely low levels,would have a detrimental impact on the phosphoric acid operation sincemuch of the equipment was rubber lined). The uranium contained in theresin, or equivalent materials or compositions, then can be removed inthe regeneration portion of the resin, or equivalent material orcomposition system.

In alternative embodiments, the loaded resin, or equivalent material orcomposition, from the primary contacting step is washed with a smallamount of water (7), which is internally contained, then transfers intothe primary pretreatment stage of the continuous contacting system.Within this portion of the contacting system the U-loaded resin, orequivalent materials or compositions, is contacted with a small amountof the alkali carbonate solution exiting the regeneration system (8) toprepare the resin, or equivalent materials or compositions, forregeneration. The spent pretreatment solution is combined with theloaded regeneration solution exiting the system.

In alternative embodiments, the pretreatment step uses a portion of theregeneration solution that initially exits the regeneration zone. Thisinitial solution has a low uranium content and effectively neutralizesany residual acid value in the resin, or equivalent materials orcompositions,. This is critical so that when the resin, or equivalentmaterials or compositions, enters the regeneration stage there is noresidual cid value that could react with the ammonium carbonate solutionand reduce its pH.

It is further noted that if there are any contained uranium values inthe pretreatment solution, this uranium will reload onto the resin, orequivalent materials or compositions, prior to its entry into theregeneration zone. This has the further effect of allowing for somelevel of uranium separation from the contained contaminants by“crowding” the ion exchange sites with uranium.

It has also been discovered that by operating a portion of thepretreatment stage in an up-flow mode the resin beds can be expandedduring each cycle. This expansion allows for regular cleaning of theresin, or equivalent materials or compositions, and enables thecontinuous ion exchange system to handle a much higher level of solidsthan either fixed bed systems or alternative solvent extraction systems.Any solids accumulated in the system are then flushed from the resin, orequivalent materials or compositions, and transferred to the spentpretreatment solution storage area, and then eventually the solids aredisposed of to the phos-acid plant's waste solids systems.

In alternative embodiments, the pretreated resin, or equivalentmaterials or compositions, is next contacted with an alkali carbonatesolution (6) to remove the uranium (U) from the resin, or equivalentmaterials or compositions, and return the resin, or equivalent materialsor compositions, to its “extraction” form. In this step the alkalicarbonate solution converts the uranium to an anionic complex for thathas no affinity for the ion exchange resin, or equivalent materials orcompositions. The uranium (U) thus transfers from the resin (orequivalent materials or compositions) phase to the alkali solutionphase. In alternative embodiments the resulting primary loadedregeneration solution (9) is then transferred to an evaporation systemto concentrate the ammonium uranyl tricarbonate solution.

Suitable carbonate solutions include ammonium carbonate, sodiumcarbonate, potassium carbonate, and the like. The choice of theappropriate solution will typically be plant specific.

In alternative embodiments, it is critical that the pH in theregeneration stage be above a minimum value. In alternative embodiments,the pH of the regeneration solution containing the uranium removed fromthe resin is above about pH 9.0, or above about pH 9.1, pH 9.2, pH 9.3,pH 9.4, pH 9.5 or pH 9.6 or more. If the pH falls below certain levelsthe uranium in the regeneration solution can reload onto the resin.

Primary Regeneration Solution Evaporation:

In alternative embodiments of the regeneration solution evaporationsystem, the loaded primary regeneration solution (9) is heated in anevaporation system using indirect steam (10) to concentrate the ammoniumuranyl tricarbonate (AUT) and decompose excess ammonium carbonate toreduce the pH of the mixture which results in a decrease in thesolubility of uranium and the formation of an ammoniumuranyl/carbonate/oxide precipitate. The ammonia resulting from thedecomposition (11B) is recovered and combined with the lean ammoniumcarbonate stream (11A). This allows for a high degree of recycle withinthe system and minimization of any resulting spent solutions.

Uranyl Precipitate Filtration/Washing/Digestion:

In alternative embodiments, the precipitated ammoniumuranyl/carbonate/oxide slurry (11) is first filtered, then the solidsare washed with a small amount of water (12). The washed filter cake isthen digested with an acid solution (13) to dissolve the uranium andproduce an ammonium uranyl salt solution. In alternative embodimentsacids that can be used include sulfuric, nitric, hydrochloric, and thelike, with sulfuric acid being preferred if the P₂O₅ facility usesH₂SO₄. The resulting uranyl salt solution (14) is then transferred tothe uranium (U) precipitation system. The lean solution, containinglower pH ammonium carbonate/bicarbonate can be recycled (11A) to theprimary “CIX system, or exemplary continuous ion exchange processing ofthe invention, and can be combined with recovered ammonia and reused.

Uranyl Salt Solution Precipitation:

In alternative embodiments, in a precipitation step, the solubleammonium uranyl salt solution (14) is combined with an alkali solution(15), such as ammonium hydroxide, to increase the pH of the solution,e.g., to a pH of about 2.5 to about pH 7.0, or between about pH 3.5 toabout pH 6. After the pH adjustment, a precipitating agent (16), forexample, a hydrogen peroxide or equivalent is added and a uranylperoxide precipitate formed (17). The peroxide slurry is thentransferred to the washing and calcining operation.

Precipitated Uranium Washing/Calcining:

In alternative embodiments, as the uranyl peroxide slurry (17) entersthis process step, a small amount of pH adjustment reagent (18) can beis added to adjust the pH of the slurry. If the pH of the slurry is low,then an alkali solution, such as ammonium hydroxide, can be used for theadjustment. If the slurry is too alkali, i.e. pH too high, then a smallamount of acid can be added, e.g. H₂SO₄, or equivalent. This mixture isthen clarified and the thickened uranyl peroxide sludge washed with asmall amount of water (19).

In alternative embodiments, the washed uranyl peroxide solids (UO₄.2H₂O)is then centrifuged and the recovered solids transferred to adryer/calciner system where the uranyl peroxide is decomposed to producea uranium oxide product (21). The centrate solution also can becollected and filtered. Some of the spent solutions are recycled toup-stream processes to minimize the overall plant aqueous spent solutionvolume (20).

In alternative embodiments, the calcined oxide product (U₃O₈) is lightlymilled then surged and loaded into drums for storage and shipment. Acontained drum loading system can be used to minimize the potential fordust emission.

Although many parts of the exemplary Dual Cycle and Single Cycleprocedures of the invention can be identical, for example, the acidcleanup, most of the primary extraction, and from the precipitation anddrying sections to the end product. In alternative embodiments, onedifference is that in the dual cycle, there is a second so-called “CIXsystem”, or exemplary continuous ion exchange processing of theinvention, whereas in the single cycle, there is no second CIX system,which is essentially replaced with evaporation of the primaryregeneration solution and a different treatment of the concentratedprimary regeneration solution to make the acidified uranyl solution(ammonium uranyl sulfate) common to both processes (line 14 in eachdiagram). From there the processes are again can be, depending on theexemplary embodiment, identical.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The following examples are to be consideredillustrative and thus are not limiting of the remainder of thedisclosure in any way whatsoever.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A process for the isolation of uranium from wetprocess phosphoric acid, the process comprising: (a) providing aphosphoric acid solution or phos-acid feedstock comprising uranium; (b)providing a continuous ion exchange system comprising a chelating orcomplexing exchange (CE) resin that binds uranium, wherein the CE resincomprises: a weakly acidic cationic exchange resin with chelating aminomethyl phosphonic acid, an aminophosphonic chelating resin, amacroporous polystyrene based chelating resin, with iminodiaceticgroups, or a composition comprising chelating groups, functionalities ormoieties that bind uranium or having iminodiacetic groups, chelatingaminomethyl phosphonic acid groups or aminophosphonic groups, whereinoptionally the composition comprises beads, wires, meshes, nanobeads,nanotubes, nanowires, or hydrogels; (c) pretreating the phosphoric acidsolution or a phos-acid feedstock using a clarification process or afiltering process to remove suspended solids, wherein the clarificationprocess or filtering process uses, an activated clay, an activatedcarbon, an activated silica, or any combination thereof; (d) applyingthe treated phosphoric acid solution or phos-acid feedstock of (c) tothe CE resin under conditions that cause the uranium to bind to the CEresin; and (e) recovering the uranium from the CE resin, with an alkalisolution to neutralize the free acid in the CE resin, followed byregenerating the CE resin with an alkali carbonate solution at a pH thatis greater than about 9.0 to produce a regenerated CE resin and aprimary loaded regeneration solution.
 2. The process of claim 1, whereinregenerating the CE resin comprises contacting the CE resin with analkali carbonate solution to convert the uranium to an anionic uranylcarbonate complex and to produce the regenerated CE resin and theprimary loaded regeneration solution comprising the anionic uranylcarbonate complex, wherein the alkali carbonate solution comprisesammonium carbonate, sodium carbonate, or potassium carbonate.
 3. Theprocess of claim 1, the process further comprising washing theregenerated CE resin with water or a slightly acidic solution prior toits reentry into uranium extraction stage of the continuous ion exchangesystem.
 4. The process of claim 2, the process further comprisingtreating the primary loaded regeneration solution in a second continuousion exchange system comprising an anion exchange (AE) resin, wherein theanionic uranyl carbonate complex is removed from the primary loadedregeneration solution.
 5. The process of claim 4, the process furthercomprising treating the AE resin with water to produce a washed AEresin.
 6. The process of claim 5, the process further comprisingtreating the washed AE resin with an acidic solution to remove theuranium from the resin by converting the anionic uranyl carbonatecomplex to a cationic form and to produce a regenerated AE resin and asecondary loaded regeneration solution containing the uranium.
 7. Themethod of claim 6, wherein the acidic solution comprises a weak sulfuricacid, nitric acid, or hydrochloric acid.
 8. The process of claim 6,wherein treating the washed AE resin with the acidic solution is carriedout in an up-flow operational mode and results in decomposition ofresidual carbonate solution in the AE resin and in production of thesecondary loaded regeneration solution containing uranium.
 9. Theprocess or method of claim 6, the process further comprising treatingthe regenerated AE resin with water.
 10. The process of claim 9, theprocess further comprising post-treating the regenerated AE resin withan alkali solution to neutralize any residual acid in the resin prior toits reentry into the secondary continuous ion exchange system.
 11. Theprocess of claim 8, the process further comprising treating thesecondary regeneration solution with an alkali solution to raise the pHof the solution from about pH 2.5 to about pH 7, or from about pH 3.5 toabout pH 6 to obtain a pH adjusted solution.
 12. The process of claim11, wherein the alkali solution comprises a sodium hydroxide or anammonium hydroxide, at a concentration ranging from 10% to about 30%;and optionally the alkali solution has a pH greater than pH
 10. 13. Theprocess of claim 11, the process further comprising adding hydrogenperoxide to the pH adjusted solution in an amount sufficient to form auranyl peroxide precipitate and to ensure complete uranyl peroxideprecipitation.
 14. The process of claim 13, the process furthercomprising separating uranyl peroxide precipitate from the pH adjustedsolution, by (i) settling, filtering, or centrifuging, followed bywashing with water, or (ii) washing on a filter or repulping with water,followed by settling, filtering, or centrifuging; and whereinoptionally, the process further comprises additional washing of theuranyl peroxide precipitate with water and optionally further washingwithin a centrifuge or repulping with water followed by settling. 15.The process of claim 14, the process further comprising drying theuranyl peroxide precipitate to form a dry solid.
 16. The process ofclaim 15, the process further comprising heating the dry solid to atemperature sufficient to decompose or calcine the dry solid to formuranium oxide.
 17. The process of claim 1, wherein the phosphoric acidsolution or phos-acid feedstock in step (a) is from a wet-processphosphoric acid.
 18. The process of claim 1, wherein the phosphoric acidsolution or phos-acid feedstock comprises uranium in any oxidationstate.
 19. A process for the isolation of uranium from wet processphosphoric acid, the process comprising: (a) providing a phosphoric acidsolution or phos-acid feedstock comprising uranium; (b) providing acontinuous ion exchange system comprising a chelating or complexingexchange (CE) resin comprising a chelating group that binds uranium; (c)pretreating the phosphoric acid solution or a phos-acid feedstock usinga clarification process or a filtering process to remove suspendedsolids, wherein the clarification process or filtering process uses anactivated clay, an activated carbon, an activated silica, or anycombination thereof; (d) applying the treated phosphoric acid solutionor phos-acid feedstock of (c) to the CE resin under conditions thatcause the uranium to bind to the CE resin; (e) pretreating the CE resinwith an alkali solution, to neutralize free acid in the resin prior toregeneration of the resin; (f) recovering the uranium and regeneratingthe CE resin with an alkali carbonate solution at a pH that is greaterthan 9.0 to convert the uranium to an anionic carbonate complex toproduce a regenerated CE resin and a primary loaded regenerationsolution; and (g) concentrating the primary loaded regeneration solutionin an evaporation unit to reduce the water content and decomposingexcess alkali carbonate to form bicarbonates and reduce the pH of thesolution, to form a uranyl precipitate.
 20. The process of claim 19,wherein the CE resin comprises: a weakly acidic cationic exchange resinwith chelating amino methyl phosphonic acid, an aminophosphonicchelating resin; a macroporous polystyrene based chelating resin, withiminodiacetic groups; or a composition comprising chelating groups,functionalities or moieties that bind uranium or having iminodiaceticgroups, chelating aminomethyl phosphonic acid groups or aminophosphonicgroups, wherein optionally the composition comprises beads, wires,meshes, nanobeads, nanotubes, nanowires, or hydrogels.
 21. The processof claim 19, the process comprising pretreating the CE resin with analkali solution comprising a portion of the primary regenerationsolution, thereby reloading uranium contained in the primaryregeneration solution onto the CE resin.
 22. The process of claim 19,wherein the regenerated CE resin is washed with water or a slightlyacidic solution prior to reentry into the continuous ion exchangesystem.
 23. The process of claim 19, the process further comprisingfiltering the uranyl precipitate, followed by washing the precipitatewith water to remove excess alkali carbonate or an entrained carbonateand/or bicarbonate solution from the uranyl precipitate.
 24. The processof claim 19, the process further comprising recovering gas evolved inthe decomposition of excess alkali carbonate with a separate waterstream, or with the filtrate, and recycling resulting solution to thecontinuous ion exchange system.
 25. The process of claim 19, the processfurther comprising digesting the uranyl precipitate with an acidsolution to produce a soluble ammonium uranyl salt solution; whereinoptionally, the acid solution comprises sulfuric acid, nitric acid, orhydrochloric acid.
 26. The process of claim 25, the process furthercomprising treating the soluble ammonium uranyl salt solution with analkali solution to raise the pH of the solution from about pH 2.5 toabout pH 7, or from about pH 3.5 to about pH 6 to obtain a pH adjustedsolution, and wherein optionally, the alkali solution comprises analkali hydroxide, and wherein optionally the alkali solution has a pHgreater than about pH
 10. 27. The process of claim 26, the processfurther comprising adding hydrogen peroxide to the pH adjusted solutionin an amount sufficient to form a uranyl peroxide precipitate and toensure complete uranyl peroxide precipitation.
 28. The process of claim27, the process further comprising separating the uranyl peroxideprecipitate from the pH adjusted solution, by (i) settling, filtering,or centrifuging, followed by washing with water, or (ii) washing theprecipitate on a filter, or repulping of the precipitate with water,followed by settling, filtering, centrifuging; and wherein optionally,the process further comprises additional washing of the uranyl peroxideprecipitate with water and optionally further washing within acentrifuge or repulping with water followed by settling.
 29. The processof claim 28, the process further comprising drying the uranyl peroxideprecipitate to form a dry solid.
 30. The process of claim 29, theprocess further comprising heating the dry solid to a temperaturesufficient to decompose or calcine the dry solid to form uranium oxide.31. The process of claim 19, wherein phosphoric acid solution orphos-acid feedstock in step (a) is from a wet-process phosphoric acid.32. The process of claim 19, wherein the phosphoric acid solution orphos-acid feedstock comprises uranium in any oxidation state.
 33. Theprocess of claim 16, wherein the uranium oxide is U₃O₈.
 34. The processof claim 30, wherein the uranium oxide is U₃O₈.